The manufacture of the conventional C type lamp string includes lamp holder and two cover parts, after integrally injecting formation respectively, copper contact pieces are thus inserted in the lamp holder, double-row power cords placed on the lamp holder by labor. Then the lamp holder is tightly pressed together with the lamp cover securely fastened. The manufacture of the conventional lamp string is labor intensive and not possible for automatic production. This has resulted in slow production speed and higher production cost. In addition, upon completion of parts assembly the necessary, storage and handling increase freight cost and waste factory space. Further because of splicing between the lamp cover and holder of the conventional C type lamp string, when influenced by external force, they could easily separate from each other to cause power leakage or a short circuit. Therefore the conventional C type lamp string is not reliable and safe for use.
In addition, the holder of the conventional C type lamp string must be made with an internal thread for locking the bulb therein so that the lamp holder and cover must be manufactured individually rather than integrally injected in one step. Further the outer design for the copper contact pieces of the conventional C type lamp string can only be constructed as a single component followed by assembly of the copper contact piece with the lamp holder by hand. Owing to the aforesaid reasons, the conventional C type lamp string can only be assembled by hand rather than by automatic production and assembly.
In view of the obvious defects found in the conventional C type lamp string, the inventor has devoted himself to seeking improvement and hence has developed the present invention through persistent testing.